Cellular radiotelephones have become increasingly popular for many different reasons, including their potential availability in case of emergency. However, conventional cellular phones fail to adequately meet emergency communication service needs because they are designed to achieve goals other than providing emergency communication services.
Emergency communication services differ from normal communication services. Emergency communication services are seldom needed, but when they are needed it is desirable that they be highly reliable and dependable. In emergency situations time is a critical factor, and emergency communication services desirably allow communication to commence with only a minimal delay. Moreover, emergency situations often are accompanied by extreme stress or panic on the part of callers, and very little mental or physical effort on the part of a caller is desirable in obtaining emergency communication services.
Stationary emergency telephones, some of which may be cellular radiotelephones, are known. However, such stationary emergency telephones are highly unsatisfactory because, in all likelihood, such an emergency phone is nowhere nearby when an emergency situation arises. Mobile radiotelephones installed in users' vehicles do a better job of providing emergency communication services than stationary telephones because they are capable of providing communication services in response to emergencies connected with vehicles and road travel. However, mobile radiotelephones are undesirably expensive for a large percentage of the population due to equipment costs, installation costs, and monthly service fees. Moreover, many emergency situations related to crime and health conditions do not occur near vehicles. Portable radiotelephones better meet the needs of emergency situations because they may be carried with a user to be readily available whenever and wherever needed.
However, even conventional portable cellular radiotelephones fail to adequately meet the needs of emergency communication services. Portable cellular radiotelephones are undesirably expensive for a large percentage of the population due to equipment costs and monthly service fees.
By FCC rule, cellular communication services are provided to a service area by up to two cellular systems, referred to as "A" and "B" systems. The majority of the population resides in service areas having both an A system and a B system. Conventional cellular radiotelephones, including portable cellular radiotelephones, are biased to favor operation on either A or B systems. In particular, conventional cellular radiotelephones are configured to operate in several different modes. Conventional cellular radiotelephones may operate only on a home system, only on A systems, only on B systems, preferably on A systems but on a B system if an A system is not available, or preferably on B systems, but on an A system if a B system is not available. None of these conventional modes of operating a cellular radiotelephone allows operation on the system with which communications are most likely to be the best. While these modes of operating cellular radiotelephones are adequate for normal communications, they are unacceptable for emergency communications because each one can lead to less reliable communication services.
Moreover, conventional portable cellular radiotelephones are intended for use in engaging in an indefinite number of calls. Accordingly, the power with which they transmit is limited to around 600 mw effective radiated power (ERP). This low power is deemed necessary to conserve battery reserves and to refrain from imposing a health hazard to the user from prolonged use. Unfortunately, this low power often leads to poor quality communication services. Often, a portable cellular radiotelephone will decide that a preferred system is available for use based upon the strength of a received signalling channel, but the portable cellular radiotelephone's transmitted signal is too weak to be received by the system. Consequently, communication services fail altogether.
Furthermore, conventional cellular radiotelephones, whether portable or not, are intended for making outgoing calls to any number of telephone numbers. Users must power-on their cellular phone, learn or know numbers to dial, discriminate keys on the radiotelephone and accurately dial the numbers, discriminate a send key from other keys and send the dialled numbers, and the like, before a system can commence setting up the call. In the stress and panic of many emergency situations this high level of user involvement is undesirable because of the likelihood of mistake and resulting time lost.